Method for actuating an image output device, method for determining tangential slice planes, actuation module and slice plane determination unit

ABSTRACT

A method is disclosed for actuating an image output device for the output of slice images, obtained from volume data, of a tissue region including at least one hollow organ section. In at least one embodiment, tangential slice planes at observation points along at least one profile line section through the hollow organ section are determined on the basis of provided volume data. In the process, the profile line section is decomposed into shorter profile line sections such that the generated profile line sections are each situated at least approximately in a plane assigned to the respective profile line section as per a predetermined quality criterion. First tangential slice planes are each assigned to the possible observation points on the associated profile line sections on the basis of these planes. A first tangential slice image is then generated from the volume data for a current observation point on the profile line section on the basis of a first tangential slice plane determined for this observation point. Control commands for the image output device are generated for the output of this slice image and transmitted to the image output device. Moreover, at least one embodiment of the invention relates to an actuation module suitable for this purpose.

PRIORITY STATEMENT

The present application hereby claims priority under 35 U.S.C. §119 onGerman patent application number DE 10 2009 006 765.5 filed Jan. 30,2009, the entire contents of which are hereby incorporated herein byreference.

FIELD

At least one embodiment of the present invention generally relates to amethod for actuating an image output device for the output of sliceimages, obtained from volume data, of a tissue region comprising atleast one hollow organ section. Furthermore, at least one embodiment ofthe invention generally relates to a method for determining tangentialslice planes at observation points along a profile line through a holloworgan section, which method can be used in the mentioned actuationmethod. Moreover, at least one embodiment of the invention generallyrelates to an actuation module for actuating an image output device anda slice plane determination unit operating according to the mentionedslice plane determination method. At least one embodiment of theinvention also generally relates to an image processing device with suchan actuation module.

BACKGROUND

In the field of medical technology, image output devices are used todisplay for a user volume data images, particularly slice images,derived from volume data of a target tissue region. By way of example,such volume data can be obtained with the aid of tomography devices,such as computed tomography scanners, magnetic resonance imagingscanners, or else other imaging devices such as ultrasoundinstallations. There are different display modes for such volume dataimages obtained from volume data. For example, they show different sliceor sectional perspectives of the imaged tissue region in differentprojections or display depths. These include the multiplanarreconstruction (MPR) and the maximum intensity projection (MIP). Themultiplanar reconstruction is a sectional imaging method in which thehollow organ is placed into a plane in a virtual fashion and shown withdepth resolution in a virtually three-dimensional fashion. By contrast,the maximum intensity projection is a sectional imaging method in whichsections of a tissue region, situated one behind the other or one abovethe other, are illustrated in a two-dimensional fashion. In the process,superimposed structures are illustrated together and a contrast isformed where that part of the tissue volume which causes the greatestmeasurement intensity in the imaging measurement produces the highestdegree of coloring in the projection illustration. Like a backprojection onto a focusing screen, structures positioned behind oneanother can in this fashion be illustrated in a plane.

An important field of application which uses volume data imagesgenerated by the abovementioned imaging devices is the diagnosis ofhollow organs or hollow organ sections, e.g. vessels, in particularcoronary vessels on the heart or vessels in the brain, or other tubularhollow organs such as the colon or the bronchi. In particular, a problemin diagnosing such structures lies in the fact that lesions can usuallybe found in edges of the hollow structure or in the walls of the holloworgan. A typical example of such a lesion is a stenotic region in avessel section.

These days, such hollow organ sections are usually diagnosed using apre-calculated profile line through the hollow organ. In the followingtext, a “profile line” is a line which follows the profile of theobserved hollow organ. This generally is a central line running rightthrough the middle of the hollow organ, the so-called “centerline”. Theliterature already discloses different relevant methods forpre-calculating such centerlines. Likewise, within the scope of computeraided diagnosis methods, there already are different methods forautomatically selecting slice planes through the hollow organ such thatpossible lesions are illustrated in the view suitable for apost-evaluation. Thus, EP 0 961 993 B1 (=WO 98/37517) describes a methodin which regions of an intestine with an abnormal wall thickness areautomatically recognized as possible lesions and are then visualized ina particularly marked fashion in a wire model. In the process, slicesare also generated along the profile line such that the lesions areclearly identifiable. U.S. Pat. No. 6,643,533 B2 suggests placing sliceimages along the profile plane through a blood vessel such that in anarrowing the smallest diameter of the blood vessel lies in the sliceplane, i.e. the slice plane is selected such that the slice image showsthe smallest lumen dimension. In the case of dilation, the slice imagecan be placed along the profile plane such that the largest diameter ofthe blood vessel is situated in the slice plane.

During the conventional diagnosis by an expert at an image outputdevice, this centerline is used as a path for a virtual movement throughthe hollow organ section. Depending on the type of profile line orcenterline calculation, this can consist of a number of individualpoints aligned next to one another, or else it can be constructed as acontinuous line or a polygonal chain. During a virtual movement throughthe hollow organ along the centerline, different slice images can thenbe displayed on a diagnosis workstation at different observation pointswhich can, for example, be the individual points from which the“centerline” is composed or, in the case of a continuous “centerline”,points at a certain step-size and can be observed by the user.

A typical screen surface for such diagnosis is illustrated in FIG. 1. Onthe left-hand side there is an image display field BF in which fourdifferent illustrations of the hollow organ section HO of interest, inthis case the right coronary artery, are illustrated. To the rightthereof there is a parameter display bar PL, acting as a user interface,on which the observer can adjust certain parameters with the aid ofmouse clicks. In this case, a three-dimensional volume image VR of theheart, in which the relevant coronary artery is clearly visible, isdisplayed at the bottom on the right-hand side of the image displayfield BF. To the left thereof an orthogonal slice OS is shown at acertain point on the “centerline” along the coronary artery (the“centerline” itself is not illustrated in this case). The two upperimages show two tangential slice images TS₁, TS₂. The orthogonal sliceplane and the tangential slice planes are selected such that theyrespectively are mutually perpendicular. Here, the orthogonal sliceplane is situated perpendicular to the profile line at a given point onthe profile line and the tangential slice planes correspond tolongitudinal slices along the hollow organ section and can be tangent tothe profile line at e.g. this point, or can comprise this point. Whenmoving along the “centerline” from one observation point to the next, anew orthogonal slice, which is perpendicular to the “centerline” at therespective observation point, and the two tangential slice images TS₁,TS₂ perpendicular thereto are illustrated at all observation points. Bymoving forward and backward along the “centerline”, for example byoperating virtual pushbuttons on the parameter display bar with the aidof the mouse pointer, the complete hollow organ section can besuccessively observed within the scope of this profile display.

However, the problem with such a conventional procedure is that thereare very big jumps in the tangential planes, particularly in the case ofstrongly curved structures and/or in the case of structures withfrequent changes in curvature. When passing through the structure alongthe profile line, this leads to a bumpy, very vigorously “shaking”display of the tangential slice images. This harbors the risk of theobserver easily losing the focus and the orientation in the image. Thiscan lead to relevant structural changes being overlooked.

SUMMARY

In at least one embodiment of the invention, an improved actuationmethod is created and, for actuating an image output device, acorresponding actuation module which permits a shaking-optimized displayor, in the ideal case, a display with as little shaking as possibleduring a profile illustration along a profile line through a holloworgan.

Accordingly, an actuation method according to at least one embodiment ofthe invention comprises at least the following:

-   -   The volume data and a profile line section through at least part        of the hollow organ section have to be provided. In the process,        the profile line section in the hollow organ or the hollow organ        section can also be set within the scope of the method, possibly        after a preceding identification and/or segmentation of the        hollow organ or the hollow organ section. The profile line can        also be successively determined in parallel while the method        according to at least one embodiment of the invention is being        performed. All that has to be available at any one time is a        sufficiently long section in which the current observation        points are situated and so the subsequently explained        plane-based decomposition for finding the optimum tangential        slice planes can be effected in a meaningful fashion.    -   Then tangential slice planes are determined at observation        points along the profile line section through the hollow organ        section, wherein the profile line section is decomposed into        shorter profile line sections such that the generated individual        profile line sections as per a predetermined quality criterion        are each situated at least approximately in an auxiliary plane.        In each case, first tangential slice planes are assigned to the        possible observation points on the associated profile line        sections on the basis of these auxiliary planes. Here, the        tangential slice plane can correspond to the respective        auxiliary plane, but it can also be slightly displaced parallel        to the respective auxiliary plane so that, for example, the        current observation point on the profile line itself is        precisely situated in the slice plane assigned to the        observation point.    -   The slice planes can be assigned directly or indirectly to the        observation points. This means that, for example, the data        required for defining the slice planes for each observation        point can be directly stored in a list. By contrast, in the case        of an indirect assignment, there first of all is for example a        reference from the observation point to the associated profile        line section. Then the definition data for the associated        tangential slice planes is assigned to each profile line section        because the tangential slice planes for all observation points        belonging to this profile line section are equal. Possible        orthogonal slice planes can then be identified or stored        individually for the individual observation points, as will be        explained in more detail below.    -   A first tangential slice image is then respectively generated        from the volume data for a current observation point on a        profile line section on the basis of a first tangential slice        plane determined for this observation point. In the process, the        current observation point can be prescribed by a user, e.g.        during diagnosis, for example with the aid of the user interface        explained above.    -   In order to output this current slice image to the user, the        control commands for the image output device are respectively        generated or derived from the data generated in the preceding        steps.    -   These control commands are then transmitted to the image output        device such that the relevant slice image can be output or        displayed thereon.

Thus, a key point of the idea is a plane-based division of the observedprofile line into individual segments such that each of these segmentsis at least approximately situated in a plane (referred to in this caseas an auxiliary plane), wherein care is preferably taken that a minimumnumber of segments is required for the complete description of theoverall profile line. Unlike the previous methods, it is thus no longerthe case that a new tangential plane is determined independently at eachindividual observation point, based only on the local curve profile, andthat the tangential slice image is generated from this and displayed.This leads to the number of jumps or fast directional changes of thetangential slice planes during a virtual movement along the profile linebeing markedly reduced. As a result of the plane-based division of theprofile line, the latter can be run-through continuously with a minimumnumber of changes of view. Hence, the display is significantly moresettled and this very much simplifies the orientation for the observer.The previously occurring shaking and jerking of the image display isavoided.

An actuation module according to at least one embodiment of theinvention comprises at least the following components:

-   -   A volume data interface for acquiring volume data. Said        interface can preferably also acquire an already previously        determined profile line section through at least part of the        hollow organ section, provided said section was generated        outside of the actuation module.    -   An input interface for acquiring observation point data, e.g.        the coordinates of a current observation point on the profile        line. This can be an interface by means of which a user can        prescribe the current observation point.    -   A slice plane determination unit for determining tangential        slice planes at observation points along at least one profile        line section through the hollow organ section which is designed        such that, during the intended operation of the actuation        module, it decomposes the profile line section into shorter        profile line sections such that the generated individual profile        line sections are each situated at least approximately in an        auxiliary plane as per a predetermined quality criterion and        first tangential slice planes are then each assigned to the        possible observation points on the associated profile line        sections on the basis of these auxiliary planes.    -   A slice image generation unit for generating a first tangential        slice image from the volume data for a current observation point        defined by the acquired observation point data on the profile        line on the basis of a first tangential slice plane determined        for this observation point.    -   A control command derivation unit for generating control        commands for the image output device.    -   An output interface for transmitting the control commands to the        image output device.

By way of example, the image output device can comprise a device driver,e.g. for a display monitor, and the control commands output by theactuation module via the output interface are such that the devicedriver is actuated in a suitable fashion. However, in principle, theactuation module itself can also contain a device driver for a displaymonitor or the like of the image output device, and so the controlcommands output by the actuation module via the output interface candirectly actuate this monitor.

The interfaces do not necessarily have to be designed as hardwarecomponents but can also be implemented as software modules, for exampleif the volume data can be acquired from another component alreadyimplemented on the same equipment, e.g. from an image reconstructionapparatus, another image processing unit or the like, or if the controlcommands only have to be transferred in software terms to anothercomponent. Likewise, the interfaces can also comprise hardware andsoftware components, for example a standard hardware interface which hasbeen configured specifically by software for this particular use.Moreover, a plurality of interfaces can also be combined together in acombined interface, for example an input-output interface.

Overall, a majority of the components for implementing the deviceaccording to at least one embodiment of the invention can wholly orpartly be implemented in the form of software modules on a processor, inparticular the slice plane determination unit, the slice imagegeneration unit and the control command derivation unit.

At least one embodiment of the present invention therefore alsocomprises a computer program product which can be loaded directly intostorage of a programmable image processing device, with program codesections for executing all steps of an actuation method according to theinvention when the program is executed in the image processing device.In the process, the image processing device can also be a component ofthe imaging system itself which is used to acquire the volume data.

Further particularly advantageous refinements and developments of atleast one embodiment of the invention emerge from the dependent claimsand the following description. In the process, the actuation module canalso be developed in accordance with the dependent claims of theanalogous actuation method.

There are various possibilities for a plane-based decomposition of theprofile line such that each segment is situated at least approximatelyin a plane, i.e. for determining the auxiliary planes or the tangentialslice planes based thereon. The determination of the tangential sliceplanes as per a method of at least one embodiment with at least thefollowing method steps is particularly preferred:

-   a) First of all, one auxiliary plane including the two end points of    the profile line section is identified, wherein a rotational angle    of the auxiliary plane about a rotational axis running through the    end points of the profile line section is selected with the aid of    an optimization method such that a defined distance measure between    the auxiliary plane and the profile line section (or the individual    points of the profile line section) is minimized. Different    possibilities for defining a suitable distance measure and different    optimization methods will still be explained below. Depending on the    distance measure and the optimization method, it is also feasible    for there to be (only) an approximate minimization of the distance    measure.-   b) Then, a “maximum distance point” on the profile line section,    which point has the greatest distance from the auxiliary plane, is    determined.-   c) This maximum distance point is analyzed as to whether the    distance of the maximum distance point from the auxiliary plane is    less than a predetermined threshold. If the distance of the maximum    distance point from the auxiliary plane does not lie below the    predetermined threshold, the profile line section at the maximum    distance point is divided into two profile line sections. The two    shorter profile line sections generated therein then respectively    run between the maximum distance point (as a new end point) and one    of the original end points of the now divided profile line section.-   d) Method steps a) to c) are respectively recursively repeated with    the newly generated profile line sections until the original profile    line section is divided into individual shorter profile line    sections, with an auxiliary plane being found for each profile line    section, the distance of which plane from a maximum distance point    of the respective profile line section lying below the predetermined    threshold. The recursion can be completed for the profile line    sections for which such an auxiliary plane which satisfies the    distance criterion has already been found. By contrast, other    profile line sections, for which the suitable auxiliary plane has    not yet been found, are again divided at the maximum distance point    and the recursion method is continued using the even shorter profile    line sections generated in the process.

e) Finally, first tangential slice planes are assigned to theobservation points situated on the respectively associated profile linesections on the basis of the obtained auxiliary planes, as alreadyexplained above, wherein this step can also be successively performedduring the recursive method for all auxiliary planes or the associatedprofile line sections for which the distance criterion has already beensatisfied.

Such a method can quickly and reliably achieve a decomposition of theprofile line section to be observed and so, on the one hand, theoriginal profile line section is only divided into a minimum number ofshorter profile line sections and, nevertheless, each of these profileline sections is situated as well as possible in a plane.

In addition to being used in the method according to at least oneembodiment of the invention, such a method for determining tangentialslice image generation planes at different observation points along aprofile line through a hollow organ section in the volume data of atissue region comprising the hollow organ section can also be utilizedin similar methods. By way of example, this method can be used in ameaningful fashion where slice images of a hollow organ are intended tobe printed out onto paper or foil for an observation on conventionalfluorescent screens, to the extent that it is desirable for slice planeswhich are as comparable as possible to be available at subsequentobservation points along a profile line for comparing slice imageprintouts. To this end, provision only has to be made for at least oneprofile line section of the hollow organ section with a first and asecond end point, and the abovementioned method for determining thetangential slice planes can then be performed. The determined tangentialslice planes or the parameters describing the slice planes can then beoutput e.g. as a result to a device for generating the slice images forthe printer or the filming station. Such a profile line section can begenerated within the scope of the method itself. However, acquisition ofan already previously determined profile line section or a completeprofile line is also possible.

In order to carry out such a slice plane determination method, theactuation module requires a slice plane determination unit with at leastthe following components:

-   -   an interface for providing at least one profile line section of        the hollow organ section with a first and a second end point.    -   An auxiliary plane determination unit which is designed such        that it carries out the following method steps when used as        intended:        -   i) identifying one auxiliary plane including the end points            of the profile line section, wherein a rotational angle of            the auxiliary plane about a rotational axis running through            the end points of the profile line section is selected using            an optimization method such that a defined distance measure            between the auxiliary plane and the profile line section is            at least approximately minimized,        -   ii) determining a maximum distance point on the profile line            section, which point has the greatest distance from the            auxiliary plane,        -   iii) analyzing whether the distance of the maximum distance            point from the auxiliary plane is less than a predetermined            threshold, and dividing the profile line section into two            profile line sections at the maximum distance point if the            distance of the maximum distance point from the auxiliary            plane does not lie below the predetermined threshold, and        -   iv) recursive continuing of method steps i) to iii) with the            profile line sections until an auxiliary plane is found for            every profile line section, the distance of which plane from            a maximum distance point of the respective profile line            section lies below the predetermined threshold.    -   A slice plane assignment unit for assigning first tangential        slice planes with observation points situated on the        respectively associated profile line sections, respectively on        the basis of the obtained auxiliary planes.

In at least one embodiment of the abovementioned method, precisely thatplane is respectively selected (as an auxiliary plane) from a cluster ofplanes passing through the start point and the end point of thecurrently observed profile line section in which the given distancemeasure is minimal. Such a cluster of planes can be described in theHesse normal form using the equation:

(n ₁ ·x+p ₁)+λ(n ₂ ·x+p ₂)=0.  (1)

Herein, x is an arbitrary position vector on the respective plane of thecluster of planes in a freely chosen coordinate system with anarbitrarily fixed origin; n₁, n₂ are two arbitrary unit vectorsorthogonal to the connecting line between the start point and the endpoint of the observed profile line section; p₁, p₂ respectivelycorrespond to the distance between the origin of the coordinate systemand the planes defined by the unit vectors n₁, n₂ which are orthonormalto these unit vectors; and A is a free parameter of the cluster ofplanes by means of which the rotational angle around the axis runningthrough the start point and the end point of the observed profile linesection can be identified.

As already mentioned above, there are different possibilities fordefining the distance measure.

In at least one variant embodiment, the distance measure between theauxiliary plane and the profile line section is determined by acombination of the Euclidean distances of points on the profile linedistance from the auxiliary plane. In a particularly preferred fashion,the Euclidean distances of points on the profile line section from theauxiliary plane can be added together in order to determine the distancemeasure between the auxiliary plane and the profile line distance.

The Euclidean distance d of an arbitrary point x₀ from a plane in theHesse normal form can be described as follows:

d({right arrow over (x)} ₀)={right arrow over (n)}·{right arrow over(x)} ₀ +p.  (2)

Herein p is the distance of the plane from the origin of the freelyselected coordinate system. With the aid of this equation, theaccumulated distance of all points on the observed profile line sectionfor each plane of the cluster of planes can be determined as follows:

$\begin{matrix}{{\sum\limits_{i = 0}^{m}\left( {{\overset{\rightarrow}{n} \cdot {\overset{\rightarrow}{x}}_{i}} + p} \right)},} & (3)\end{matrix}$

wherein m is the number of points on the observed profile line section.In the case of a profile line prescribed in a discrete fashion fromindividual points, this simply is the number of points on the relevantprofile line section. In the case of a continuously prescribed profileline, for example a parameterized curve, m can be given by the length ofthe observed profile line section divided by a predetermined step-sizeby means of which a user can step forward or back along the profile lineduring the observation.

Thus, in order to eliminate the free parameter λ of the cluster ofplanes from the above equation (1) within the scope of at least oneembodiment of the optimization method, it follows that the accumulateddistance for each plane of the cluster of planes, i.e. the sum of thedistances of the points of the profile line section, can be determinedas per equation (3) and that plane can then be selected which has thesmallest accumulated distance.

In a particularly simple optimization method of at least one embodiment,such a calculation is performed for a discrete number of planes, whichrespectively differ from one another in respect of the rotational angleλ by a certain step-size. By way of example, the angle λ can be variedin 1° steps and the distance measure can in each case be calculated forthe plane that is generated. Using currently available computers, itgoes without saying that such a calculation can be performed in realtime.

Alternatively, it is also possible for other optimization methods to beused, such as, for example, gradient methods (also referred to “methodsof steepest descent”) or so-called hill climbing or downhill searchmethods, in particular the downhill simplex method.

In addition to adding together the individual Euclidean distances of thepoints to the respective profile line section, it is also possible forother combinations of the distances, for example the sum of the squaresor the like, to be used.

An alternative, very simple distance measure is based on the use of aEuclidean distance between a centroid of the profile line section andthe respective auxiliary plane. The centroid of a profile line sectionemerges as the arithmetic mean of all points on this profile linesection:

$\begin{matrix}{{\frac{1}{m}{\sum\limits_{i = 0}^{m}{\overset{\rightarrow}{x}}_{i}}},} & (4)\end{matrix}$

where m again is the number of points on the observed profile linesection.

Provided that a profile line section which is now intended to beassociated with a matching slice plane is approximately a straight-linesegment after decomposition, a multiplicity of planes can emerge forwhich the optimization criterion is satisfied; in the extreme case of anexactly straight-line segment this can even be an infinite number ofplanes. Therefore, the rotational angle of an auxiliary plane, whichbelongs to a basically (i.e. approximately) straight profile linesection, is selected taking into account the orientation of theauxiliary planes of adjacent profile line segments. In a particularlypreferred fashion, the mean value of the rotational angle of theauxiliary planes of the adjacent profile line section is then used asthe rotational angle of this auxiliary plane, since in this fashion atransition which is as smooth as possible is ensured between the planesor slice images belonging to the individual adjacent profile linesections.

As already mentioned initially, at an observation point, a slice imageorthogonal to the profile line at the respective observation point isalso particularly preferably generated from the volume data in additionto the first tangential slice image, and corresponding control commandsfor the image output device are derived for the output of thisorthogonal slice image and transmitted to the image output device. In acorresponding fashion, a second tangential slice image rotated by 90°with respect to the first tangential slice image is preferably alsogenerated from the volume data in addition to the first tangential sliceimage, and corresponding control commands for the image output deviceare derived for the output of this second tangential slice image andtransmitted to the image output device. That is to say that in apreferred embodiment of the method according to at least one embodimentof the invention, one orthogonal slice plane and two tangential sliceplanes are therefore determined along a profile line section for each ofthe possible observation points of the profile line section, andcorresponding stacks of slice images are assembled which are thensuccessively called one after the other during a later observation whenthe individual observation points are approached in a virtual fashion.

It is possible for very diverse slice images to be generated in theprocess, preferably the above-mentioned multiplanar reconstructions (MPRimages) or maximum intensity projections (MIP images). In principle, itis also possible for different slice images to be generated for eachpoint and the user then selectively selects one or the otherillustration or a combination of these illustrations—for example oneillustration variant in the first tangential slice plane and a differentillustration variant in a different slice image plane.

In principle, the invention can be applied in any type of, in particulartubular, hollow organs. The method can be applied particularly gainfullyin the field of imaging brain supply structures, for example the Carotidartery, or in imaging coronary arteries.

A particular advantage emerges if such volume data, which representsregions which exist outside of the direct functional relationship withthe hollow organ, is eliminated computationally from the volume imagefor the image display of the volume image. Such segmentation within thevolume data, which is intended to address only the use of the importantvolume data regions for the illustration of the hollow organ, inparticular excludes the possibility of bothersome structures such asbone structures in the surrounding area making the illustration moredifficult for the user, as a result of which errors in the recognitioncan be avoided during the search for conspicuous structures.

In principle, the actuation method according to at least one embodimentof the invention can be performed in a fully-automated fashion, forexample with the aid of recognition programs for automaticallyrecognizing certain hollow organs, as are offered by the Vital Imagescompany, and which also generate the profile lines of hollow organsautomatically. However, it is preferable for the profile line to beoutput to a user for the purposes of modification. Within the scope ofsuch a semi-automatic process, the actuation module thus obtainsmodification information via an interface. In principle, thismodification information can also originate from input sources otherthan human input sources, for example from external data processingunits.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, the invention will once again be explained withreference to the attached figures and on the basis of exampleembodiments. In the process, the same components in the various figuresare in part provided with identical reference figures. In particular,

FIG. 1 shows an illustration of the user interface of a diagnosisworkstation as per the prior art when observing a right coronary arterywith three mutually orthogonal slice images being illustratedsimultaneously,

FIG. 2 shows a flowchart of a possible procedure of a method accordingto an embodiment of the invention,

FIG. 3 shows a two-dimensional, very much simplified illustration of theprinciple of recursive decomposition of a profile line,

FIG. 4 shows a three-dimensional illustration of a profile linedecomposed into individual profile line sections with the respectivelyassociated tangential slice planes, and

FIG. 5 shows a simplified block illustration of a possible embodiment ofan actuation module according to the invention.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Various example embodiments will now be described more fully withreference to the accompanying drawings in which only some exampleembodiments are shown. Specific structural and functional detailsdisclosed herein are merely representative for purposes of describingexample embodiments. The present invention, however, may be embodied inmany alternate forms and should not be construed as limited to only theexample embodiments set forth herein.

Accordingly, while example embodiments of the invention are capable ofvarious modifications and alternative forms, embodiments thereof areshown by way of example in the drawings and will herein be described indetail. It should be understood, however, that there is no intent tolimit example embodiments of the present invention to the particularforms disclosed. On the contrary, example embodiments are to cover allmodifications, equivalents, and alternatives falling within the scope ofthe invention. Like numbers refer to like elements throughout thedescription of the figures.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments of thepresent invention. As used herein, the term “and/or,” includes any andall combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being“connected,” or “coupled,” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected,” or “directly coupled,” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between,” versus “directly between,” “adjacent,” versus“directly adjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments of the invention. As used herein, the singular forms “a,”“an,” and “the,” are intended to include the plural forms as well,unless the context clearly indicates otherwise. As used herein, theterms “and/or” and “at least one of” include any and all combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “comprises,” “comprising,” “includes,” and/or“including,” when used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, term such as “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein are interpreted accordingly.

Although the terms first, second, etc. may be used herein to describevarious elements, components, regions, layers and/or sections, it shouldbe understood that these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are used onlyto distinguish one element, component, region, layer, or section fromanother region, layer, or section. Thus, a first element, component,region, layer, or section discussed below could be termed a secondelement, component, region, layer, or section without departing from theteachings of the present invention.

As mentioned initially, FIG. 1 shows, at the top and in the left-handlower half of the image in the image display field BF, two tangentialslice images TS₁, TS₂ and an orthogonal slice image OS at an observationpoint on a profile line through the right coronary artery. Theserespectively are multiplanar reconstructions. The right-hand lower halfof the image shows a three-dimensional volume image VR of the heart withthe right coronary artery on the basis of the volume renderingtechnique. This form of illustration shows the currently conventionalindustry standard for illustrating volume data or slice images for auser. In the process, the multiplanar reconstructions show slices inthree mutually perpendicular planes of the same tissue region within theheart which is shown in the three-dimensional volume image VR. In eachof the individual slice images TS₁, TS₂, OS, two reference axes situatedperpendicularly with respect to one another are usually shown (notvisible in the illustration shown here) and they represent theobservation planes of the respective other two slice images. Such sliceimages have already been stored for every observation point on theprofile line through the coronary artery, or they can be generatedaccordingly. The observer can run along the profile line fromobservation point to observation point by appropriate control commandsand “scroll” through the slice image stack in the process.

FIG. 2 illustrates how the method according to an embodiment of theinvention can ensure that, in the case of such an observationrun-through along a profile line, the tangential slice images TS₁, TS₂no longer shake as frequently and as vigorously as in the conventionaldisplay methods and so an observation run-through with a smootherdisplay is possible for the observer.

In method step I, the method first of all starts with the provision ofvolume data of the region of interest—in this case, for example, theheart with the coronary artery to be observed. In method step II, thehollow organ is then identified in the volume data, wherein segmentationin particular is also possible. Within the scope of an embodiment of themethod, this method step II is optional because it is also possiblethat, for example, only the volume data of the relevant hollow organ isalready provided in step I, for example if identification andsegmentation was performed previously within the scope of other methods.

At least one profile line piece through the hollow organ section to beobserved is then determined in step III. In the process, this is usuallythe “centerline”. Therefore, without loss of generality, the term“centerline” is used to mean the same as “profile line” in the followingtext. This step III is also optional within the scope of the methodbecause it is also possible for the centerline to be prepared in advancetogether with the volume data.

The actual recursive method for decomposing the observed centerlinesection into the centerline segments then begins in step IV. Herein, astraight line is firstly placed through the end points of the centerlinesection, which are of course known from step III (or a previousrecursion step), and an auxiliary plane including the end points isdefined and can be rotated by a rotational angle λ about the straightline as axis of rotation.

In step V, the rotational angle λ is then optimized such that, in thefashion according to an embodiment of the invention, a defined distancemeasure between the auxiliary plane and the observed centerline sectionis minimized. By way of example, the distance of all centerline pointson the observed centerline section from the auxiliary plane, accumulatedaccording to equation (3), can be calculated for this, and, in theprocess, there can be an optimization of this distance as a function ofthe rotational angle λ with the aid of a gradient descent method.

The point referred to as the maximum distance point of the optimumauxiliary plane found in this fashion is then determined on the observedcenterline section in step VI, which point has the greatest distancefrom the optimized auxiliary plane. Equation (2) can be used for this.

Step VII analyzes whether the distance DM of the maximum distance pointfrom the optimized auxiliary plane, determined in step VI, lies below acertain distance threshold DG. If this is not the case, the pathreferred to by “N” is chosen in FIG. 2 and the recursive loop overmethod steps IV, V, VI, VII is continued being run through. In theprocess, the current profile line section is, in step VIII, first of alldivided into two shorter centerline segments at the maximum point. Forall centerline segments generated in this fashion, steps IV, V, VI andVII are then performed again.

In the process, the query in step VII is performed separately for eachof the generated segments. Steps VIII, IV, V, VI and VII of therecursion method are run through again for those segments which do notyet satisfy the condition as per step VII. By contrast, the auxiliaryplane corresponding to those centerline segments which satisfy thecondition is already stored in a storage 10 in step IX, or the datarequired to define this auxiliary plane is stored (path “Y”). However,the next step X is generally only performed when step VII determinesthat the criterion is satisfied for all auxiliary planes, i.e. that thecomplete original centerline section was decomposed such thatcorresponding auxiliary planes which satisfy the distance criterion werefound for all currently existing centerline sections and the auxiliaryplanes or the data thereof were/was stored in the storage 10 in step IX,even for the last centerline sections.

The entire method from step I to step IX can also be performed beforeactually observing the data, that is to say in a fully automatic fashionwhen for example calling an observation or diagnosis program, withoutinteractive user interventions.

The observation point data BPD which defines a current observation pointon the centerline is then acquired in step X. This can for example beperformed by the input of an observer at a terminal of an imageprocessing device 1 with a corresponding user interface, for example akeyboard or a graphical user interface.

Then corresponding slice images are generated in step X in the sliceimage planes predetermined for this observation point, wherein use canin turn be made of the slice image planes which are stored in thestorage 10 and assigned to the individual observation points.

Reference is made to the fact that not only the slice images can bestored in the storage 10 in step IX, but that in principle a matchingslice image can be generated here for every slice plane and thecompleted slice images can be stored in the storage 10. Then, all thatis required in step X is that these slice images are called.

Finally, the control commands are generated in step XI in order tooutput the generated slice images, for example in the form illustratedin FIG. 1, on a monitor of the terminal 2, which in this case serves asa display device.

In order to clarify the method, FIG. 3 illustrates the cursivedecomposition of a centerline section VA between two end points EP₁ andEP₂ in a very simplified fashion (in an initial step, two intermediatesteps and a final step in accordance with the arrows between theindividual images). Herein, it should be noted that only atwo-dimensional illustration was selected for reasons of simplicity andso the essential part of the optimization of the angle λ of theauxiliary plane H₁ about an axis running through the end points EP₁, EP₂is not illustrated. To this end, reference is made to FIG. 4, which willstill be explained below. However, in FIG. 3 it is clearly visible howrespectively one maximum distance point MP₁, MP₂, . . . on the currentlyobserved centerline section from the auxiliary plane is determined andhow the currently observed centerline section is divided into twoshorter centerline sections at this maximum distance point MP₁, MP₂, . .. .

Therefore, the maximum distance point MP₁ is first of all determined inthe first step, and this is then followed in the next step by adecomposition into two centerline sections VA′, VA″ with two own, newauxiliary planes H₂, H₃, wherein the maximum distance point MP₂ from theassociated auxiliary plane H₃ is found simultaneously for the centerlinesection VA″. In the next step, this centerline section VA″ is thendecomposed at the new maximum distance point MP₂ into two in turnshorter centerline sections which are now assigned the auxiliary planesH₄ and H₅. At the same time, it can be seen for the middle centerlinesection with the auxiliary plane H₄ how a new maximum distance point MP₃is determined for this. What is then illustrated in the final step ofFIG. 3 is how the overall centerline section VA was divided into manyshorter centerline sections which respectively run from one maximumdistance point MP₁, MP₂, MP₃, MP₄, MP₅, MP₆ (determined in a precedingrecursion step) to the next, wherein the individual small centerlinesections in each case already can be approximated relatively well to theindividual auxiliary planes.

For this, FIG. 4 shows a perspective three-dimensional illustration of acompletely decomposed profile line V. In this context, the profile lineV is decomposed into a total of five profile line sections VA₁, VA₂,VA₃, VA₄, VA₅ which respectively extend between two end points E₀, E₁,E₂, E₃, E₄, E₅. A slice plane S₁, S₂, S₃, S₄, S₅ assigned to therespective centerline section VA₁, VA₂, VA₃, VA₄, VA₅ is sketchedbetween the end points E₀, E₁, E₂, E₃, E₄, E₅ of each centerline sectionVA₁, VA₂, VA₃, VA₄, VA₅, which slice plane includes the respectivelyassociated end points E₀, E₁, E₂, E₃, E₄, E₅ of the relevant centerlinesection VA₁, VA₂, VA₃, VA₄, VA₅, and the rotational angle λ of whichslice plane about an axis running through the respective end points E₀,E₁, E₂, E₃, E₄, E₅ is selected such that the respective centerlinesection VA₁, VA₂, VA₃, VA₄, VA₅ is approximately situated as well aspossible in the respective slice plane S₁, S₂, S₃, S₄, S₅.

FIG. 4 also shows that the profile line V consists of individualobservation points BP. The method according to an embodiment of theinvention now ensures that, in the case of navigation from oneobservation point BP to the next observation point BP, the assignedtangential slice plane S₁, S₂, S₃, S₄, S₅ does not change in the vastmajority of cases and so a smoother image display is possible during arunning-through observation of the hollow organ. The slice planes S₁,S₂, S₃, S₄, S₅ are only switched at the end points E₁, E₂, E₃, E₄ and soa jump in the illustration of the tangential slice images can, if atall, only be expected here.

FIG. 5 shows an example of an image processing device 1 according to anembodiment of the invention with an actuation module 5 according to theinvention and an image output device 3. The image output device 3 is themonitor 3 of a terminal 2 which is conventionally used for the diagnosisand is also equipped with a user interface 4, for example in the form ofa keyboard and/or a mouse (not illustrated) in this case, whichinteracts with a graphical user interface on the monitor 3. Theactuation module 5 can be implemented in the form of a hardware andsoftware combination on a processor of this terminal 2; this isindicated in FIG. 5 by the dashed line.

Here, the actuation module 5 has a volume data interface 6 in order toacquire volume data VD comprising the desired hollow organ 1. Thisvolume data VD is then for example transferred to a hollow organdetermination unit 7 in order to identify and possibly segment thehollow organ in the volume data. A profile line determination unit 8then identifies a profile line, for example the centerline, through thehollow organ and corresponding profile line section data VAD definingthe identified centerline section is transmitted to a slice planedetermination unit 9 according to an embodiment of the invention. Itshould also be noted in this case that the hollow organ determinationunit 7 and the profile line identification unit 8 are optional and thisdata can also be acquired together with the volume data by means of theinterface 6.

The profile line section data VAD defining the centerline section isacquired from an interface 15 in the slice plane determination module 9,wherein this interface generally is a virtual program interface 15 whichacquires this data directly from the interface 6 or the profile lineidentification unit 8. The data is then fed to an auxiliary planedetermination unit 16 which determines the auxiliary planes as describedabove. Components of this auxiliary plane determination unit 16implemented purely in the form of software can for example be anoptimization unit 19, for respectively determining one auxiliary planewith an optimum rotational angle between the end points of the profileline sections, and a maximum distance point determination unit 20, whichdetermines the maximum distance point and the distance thereof from theoptimized auxiliary plane. An analyzing unit 21 can be a furthercomponent and it analyzes whether the distance of the maximum distancepoint from the auxiliary plane lies below the predetermined threshold.These components 19, 20, 21 are designed such that the recursive methodis performed according to an embodiment of the invention and thus acenterline section acquired from the interface 15 was decomposed intothe required shorter centerline sections. Then a slice plane assignmentunit 17 is used to directly or indirectly assign the obtained auxiliaryplanes with the respective observation points on the individualcenterline sections as tangential slice planes. In this case, it shouldbe noted that the slice plane assignment unit 17 and the auxiliary planedetermination unit 16 can also be formed as a combined unit.

The respectively found tangential slice planes for the individualobservation points are then stored in a storage 10 via a furtherinterface 18, as was described above.

The actuation module 5 also has a slice image generation unit 11. Thisslice image generation unit 11 receives observation point data BPD, thatis to say the coordinates of the current observation point on thecenterline, from the terminal 2 via, for example, an interface 13 and itrespectively generates for this point, on the basis of the tangentialslice planes assigned to the individual observation points BP, oneorthogonal slice image and two mutually perpendicular tangential sliceimages using the volume data VD which can be acquired from the interface6.

The image data preferred in this case is then transferred to a controlcommand derivation unit 12 of the actuation module 5; said unitgenerates the control commands for the image output device 3 andtransmits these control commands SB to the terminal 2 or the monitor 3thereof via an output interface 14. As a result of this, the driver ofthe monitor 3 is for example actuated such that the slice images aresuitably displayed on the monitor 3, for example in the form illustratedin FIG. 1.

Finally, reference is once again made to the fact that the methoddescribed in detail above and the illustrated apparatuses are merelyexample embodiments which can be modified in a wide variety of ways by aperson skilled in the art without departing from the scope of theinvention. Furthermore, the use of the indefinite article “a” or “an”does not preclude the relevant features from also being present inplural form. Likewise, the terms “unit” and “module” do not preclude therelevant components from consisting of a plurality of interactingsub-components, which can possibly also be distributed in space.

The patent claims filed with the application are formulation proposalswithout prejudice for obtaining more extensive patent protection. Theapplicant reserves the right to claim even further combinations offeatures previously disclosed only in the description and/or drawings.

The example embodiment or each example embodiment should not beunderstood as a restriction of the invention. Rather, numerousvariations and modifications are possible in the context of the presentdisclosure, in particular those variants and combinations which can beinferred by the person skilled in the art with regard to achieving theobject for example by combination or modification of individual featuresor elements or method steps that are described in connection with thegeneral or specific part of the description and are contained in theclaims and/or the drawings, and, by way of combineable features, lead toa new subject matter or to new method steps or sequences of methodsteps, including insofar as they concern production, testing andoperating methods.

References back that are used in dependent claims indicate the furtherembodiment of the subject matter of the main claim by way of thefeatures of the respective dependent claim; they should not beunderstood as dispensing with obtaining independent protection of thesubject matter for the combinations of features in the referred-backdependent claims. Furthermore, with regard to interpreting the claims,where a feature is concretized in more specific detail in a subordinateclaim, it should be assumed that such a restriction is not present inthe respective preceding claims.

Since the subject matter of the dependent claims in relation to theprior art on the priority date may form separate and independentinventions, the applicant reserves the right to make them the subjectmatter of independent claims or divisional declarations. They mayfurthermore also contain independent inventions which have aconfiguration that is independent of the subject matters of thepreceding dependent claims.

Further, elements and/or features of different example embodiments maybe combined with each other and/or substituted for each other within thescope of this disclosure and appended claims.

Still further, any one of the above-described and other example featuresof the present invention may be embodied in the form of an apparatus,method, system, computer program, computer readable medium and computerprogram product. For example, of the aforementioned methods may beembodied in the form of a system or device, including, but not limitedto, any of the structure for performing the methodology illustrated inthe drawings.

Even further, any of the aforementioned methods may be embodied in theform of a program. The program may be stored on a computer readablemedium and is adapted to perform any one of the aforementioned methodswhen run on a computer device (a device including a processor). Thus,the storage medium or computer readable medium, is adapted to storeinformation and is adapted to interact with a data processing facilityor computer device to execute the program of any of the above mentionedembodiments and/or to perform the method of any of the above mentionedembodiments.

The computer readable medium or storage medium may be a built-in mediuminstalled inside a computer device main body or a removable mediumarranged so that it can be separated from the computer device main body.Examples of the built-in medium include, but are not limited to,rewriteable non-volatile memories, such as ROMs and flash memories, andhard disks. Examples of the removable medium include, but are notlimited to, optical storage media such as CD-ROMs and DVDs;magneto-optical storage media, such as MOs; magnetism storage media,including but not limited to floppy disks (trademark), cassette tapes,and removable hard disks; media with a built-in rewriteable non-volatilememory, including but not limited to memory cards; and media with abuilt-in ROM, including but not limited to ROM cassettes; etc.Furthermore, various information regarding stored images, for example,property information, may be stored in any other form, or it may beprovided in other ways.

Example embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. A method for actuating an image output device for the output of slice images, obtained from volume data, of a tissue region comprising at least one hollow organ section, comprising: providing the volume data and a profile line section through at least part of the hollow organ section; determining tangential slice planes at observation points along at least one profile line section through the hollow organ section, wherein the at least one profile line section is divided into relatively shorter profile line sections such that the relatively shorter profile line sections are each situated at least approximately in an auxiliary plane assigned to the respective at least one profile line section as per a quality criterion, and wherein first tangential slice planes are each assigned to possible observation points on the associated relatively shorter profile line sections on the basis of the auxiliary planes; generating at least one first tangential slice image from the volume data for each respective observation point on the profile line section on the basis of a first tangential slice plane determined for the respective observation point; generating control commands for the image output device for the output of the generated at least one first tangential slice image; and transmitting the control commands to the image output device.
 2. The method as claimed in claim 1, wherein tangential slice planes at observation points along the profile line section are determined using at least the following: a) identifying one auxiliary plane including two end points of the profile line section, wherein a rotational angle of the auxiliary plane about a rotational axis running through the end points of the profile line section is selected using an optimization method such that a defined distance measure between the auxiliary plane and the profile line section is minimized, b) determining a maximum distance point, on the profile line section, which has a relatively greatest distance from the auxiliary plane, c) analyzing whether the distance of the maximum distance point from the auxiliary plane is less than a threshold, and dividing the profile line section into two profile line sections at the maximum distance point if the distance of the maximum distance point from the auxiliary plane does not lie below the threshold, d) recursive continuing of method steps a) to c) with the profile line sections until an auxiliary plane is found for each of the relatively shorter profile line sections generated in the process, the distance of which plane from a maximum distance point of the respective relatively shorter profile line section lying below the threshold, and e) respectively assigning first tangential slice planes to observation points situated on the respectively associated relatively shorter profile line sections on the basis of the obtained auxiliary planes.
 3. The method as claimed in claim 2, wherein the distance measure between the auxiliary plane and the profile line section is determined by combining the distances of points on the profile line section from the auxiliary plane.
 4. The method as claimed in claim 3, wherein the distances of points on the profile line section from the auxiliary plane are added together in order to determine the distance measure between the auxiliary plane and the profile line section.
 5. The method as claimed in claim 2, wherein the distance measure is determined on the basis of a distance of a centroid of the profile line section from the auxiliary plane.
 6. The method as claimed in claim 2, wherein the rotational angle of an auxiliary plane which is associated with a basically straight profile line section is selected taking into account the orientation of the auxiliary planes of adjacent profile line sections.
 7. The method as claimed in claim 6, wherein the rotational angle of an auxiliary plane which is associated with a basically straight profile line section corresponds to the mean value of the rotational angles of the auxiliary planes of the adjacent profile line sections.
 8. The method as claimed in claim 1, further comprising: generating, in addition to the first tangential slice image from the volume data, at least one of a slice image orthogonal to the profile line at the respective observation point and a second tangential slice image rotated by 90° with respect to the first tangential slice image, deriving corresponding control commands for the image output device for the output of at least one of the orthogonal slice image and the second tangential slice image, and transmitting the derived commands to the image output device.
 9. The method as claimed in claim 1, wherein the slice image comprises a multi-planar reconstruction or a maximum intensity projection.
 10. A method for determining tangential slice planes at observation points along a profile line through a hollow organ section in volume data of a tissue region including at least the hollow organ section, comprising: a) providing at least one profile line section of the hollow organ section with a first and second end point; b) identifying one auxiliary plane including the end points of the at least one profile line section, wherein a rotational angle of the auxiliary plane about a rotational axis running through the end points of the at least one profile line section is selected using an optimization method such that a defined distance measure between the auxiliary plane and the at least one profile line section is minimized; c) determining a maximum distance point on the at least one profile line section, the determined maximum distance point having a relatively greatest distance from the auxiliary plane; d) analyzing whether a distance of the maximum distance point from the auxiliary plane is less than a threshold, and dividing the at least one profile line section into two profile line sections at the maximum distance point if the distance of the maximum distance point from the auxiliary plane does not lie below the threshold; e) recursive continuing of method steps b) to d) with the two profile line sections until an auxiliary plane is found for each at least one profile line section, the distance of the auxiliary plane from a maximum distance point of a respective at least one profile line section lying below the threshold; and f) respectively assigning first tangential slice planes to observation points situated on the respectively associated at least one profile line section on the basis of the obtained auxiliary planes.
 11. An actuation module for actuating an image output device for the output of slice images, obtained from volume data, of a tissue region comprising at least one hollow organ section, the actuation module comprising: a volume data interface to acquire volume data; an input interface to acquire observation point data; a slice plane determination unit to determine tangential slice planes at observation points along at least one profile line section through the at least one hollow organ section which is designed such that the at least one profile line section is divided into relatively shorter profile line sections such that the relatively shorter profile line sections are each situated at least approximately in an auxiliary plane assigned to a respective relatively shorter profile line section as per a quality criterion and first tangential slice planes are each assigned to the possible observation points on the associated relatively shorter profile line sections on the basis of these auxiliary planes; a slice image generation unit to generate a first tangential slice image from the volume data for a current observation point on the at least one profile line on the basis of a first tangential slice plane determined for the current observation point; a control command derivation unit to generate control commands for the image output device; and an output interface to transmit the control commands to the image output device.
 12. A slice plane determination unit for determining tangential slice planes at observation points along a profile line through a hollow organ section in volume data of a tissue region comprising at least the hollow organ section, comprising: a) an interface to provide at least one profile line section of the hollow organ section with a first and a second end point; b) an auxiliary plane determination unit to: i) identify one auxiliary plane including the end points of the at least one profile line section, wherein a rotational angle of the auxiliary plane about a rotational axis running through the end points of the at least one profile line section is selected using an optimization method such that a distance measure between the auxiliary plane and the at least one profile line section is at least approximately minimized, ii) determine a maximum distance point on the at least one profile line section, the maximum distance point having a relatively greatest distance from the auxiliary plane, iii) analyze whether a distance of the maximum distance point from the auxiliary plane is less than a threshold, and divide the at least one profile line section into at least two profile line sections at the maximum distance point if the distance of the maximum distance point from the auxiliary plane does not lie below the threshold, and iv) recursively continue steps i) to iii) with the at least two profile line sections until an auxiliary plane is found for each of the at least two profile line sections, the distance of which plane from a maximum distance point of a respective profile line section lies below the threshold; and c) a slice plane assignment unit to assign first tangential slice planes with observation points situated on the respectively associated profile line sections, respectively on the basis of the obtained auxiliary planes.
 13. An image processing device comprising: an image output device; and an actuation module as claimed in claim 11 to actuate the image output device.
 14. A computer program product which is directly loadable into a storage of a programmable image processing device, including program code sections for executing the method as claimed in claim 1 upon the program being executed in the image processing device.
 15. A computer program product which is directly loadable into a storage of a programmable image processing device, including program code sections for executing the method as claimed in claim 10 upon the program being executed in the image processing device.
 16. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim
 1. 17. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim
 10. 